Hi I want to use the sdram controller but it requires an avalon master. I have been trying to create one with SOPC builder in verions 7.2 quartus. Could someone perhaps just give a list of points indicating how one does this and gets the master to link to the controller?

Hi notme: It depends on what you are doing. First You'll want to read the Avalon bus specification: www.altera.com/literature/manual/mnl_avalon_spec.pd And define your master device in verilog/vhdl. If you are just hooking this up to the NIOS CPU, the CPU has a master port already, so you don't have to create your own, but if you are hooking it up to some other CPU and/or dedicated logic, the master connectivity is defined by the spec. However there are several valid master types, so you'll should read though it and understand what you need. Once you have the the Master component defined, you go into SOPC builder, and define the component. This basically tells SOPC builder what signals are Avalon/clock/reset/etc, and what signals are exports that go to the top of the SOPC system. Once this is done, you can add the component to your SOPC system. Now with SOPC builder, you have connectivity between various master and slave devices that you can click on. Once completed, you generate the modules, and it produces a SOPC level that you can import into your top module and finish any non-sopc connectivity. (IE it generates all the arbiters/muxes/domain crossing logic necessary depending on the complexity of the system) Pete Once you mast

Thanks for Post. I am still a bit confused. I have an external micro that I want to connect to the SDR Dram controller in SOPC. For this I need an Avalon master. I have made a few attempts at this but am not sure about a few things.... 1. How do I know which Avalon signals the DRAM IP requires. I have looked at the docs and they dont say??? 2. Do I then define the external micros address,data and control lines in my component as "export" signals in SOPC? 3. Is there a recommended method of connecting my address,data and control lines to the Avalon address,data and control lines?

Hi notme: --- Quote Start --- 1. How do I know which Avalon signals the DRAM IP requires. I have looked at the docs and they dont say??? --- Quote End --- You can bet the DRAM IP Is a slave with byteenables. However there are various types of slaves, Most likely it will have a data valid as well. However, the exact inter-connectivity will be handled by SOPCbuilder. You just need to make sure your Master supports byteenables if you need to do transactions less than a full word. If you only due word sized transactions, you may due bursting, but care should be done to insure you align your allowed burst size and address alignment, so that the you don't have unintended line-wraps. --- Quote Start --- 2. Do I then define the external micros address,data and control lines in my component as "export" signals in SOPC? --- Quote End --- Yes. --- Quote Start --- 3. Is there a recommended method of connecting my address,data and control lines to the Avalon address,data and control lines? --- Quote End --- Not really, It's usually a depends on the uP. Like with TI, you have an EMIF bus, so the timing/strobe is slightly different, a bit of logic to interface the too, but it isn't too significant. Once you have the "Bridge" from your CPU to Avalon interface, you can then click on any avalon slave device to the bus and SOPC builder handles all the interconnect.

Thanks - I have tried that but SOPC gives warning like.... m0 Must have address signal. Which address signal is it talking about? The signals going to the Avalon slave dram controller or the signal going to my external cpu? Perhaps you could clarify the signals.. My external address bus is in the Name column, what should be in the Interface column? There is a drop down with many options, should this be the export_0 option?

--- Quote Start --- Thanks - I have tried that but SOPC gives warning like.... m0 Must have address signal. Which address signal is it talking about? The signals going to the Avalon slave dram controller or the signal going to my external cpu? Perhaps you could clarify the signals.. My external address bus is in the Name column, what should be in the Interface column? There is a drop down with many options, should this be the export_0 option? --- Quote End --- In you Bridge interface between your CPU and Avalon bus, you should have as a minimum the following Avalon master should have a minimum of : clk waitrequest Address, ReadData, Writedata, read and write signals. These should be defined under the Avalon Master type. The CPU interface signasl, which depending on the CPU type may include Address, Data, read and Write signals as well, will all be defined as export signals.

Creating an Avalon Master - Please Help | Altera Community

19 Replies

Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
You cannot directly connect an external device with the Avalon Master. You need to create a Tri-state bridge before you can connect the device to the bus.

--- Quote End ---

I dont quite follow this. According to the SOPC docs I need a master if I use the SDRAM IP. If this is the only slave why do I need a bridge? I thought that the bridge was to allow for multiple slaves? The docs imply that I can create my own master which is what I have done. The system compiles in SOPC without warning or errors. I have not tested it yet.

So are you saying that I need the bridge component between the external micro and my master device?
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
Is the Avalon bridge a free IP core?
--- Quote End ---

Tri-state Avalon bridge is freely available with SOPC Builder. It is a part of the bus fabric.
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
I dont quite follow this. According to the SOPC docs I need a master if I use the SDRAM IP. If this is the only slave why do I need a bridge? I thought that the bridge was to allow for multiple slaves? The docs imply that I can create my own master which is what I have done. The system compiles in SOPC without warning or errors. I have not tested it yet.

So are you saying that I need the bridge component between the external micro and my master device?
--- Quote End ---

The bridge is required when you want to connect an external (i.e. off-chip) peripheral. If you have an on-chip peripheral, then you don't need the tri-state bridge. In your specific case, if your SDRAM is an *external* chip which would communicate with the SOPC/NIOS system on the FPGA, then you certainly need a bridge. If the SDRAM is an on-chip component, say an IP core or an HDL design, then you don't have to use the bridge.
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
Tri-state Avalon bridge is freely available with SOPC Builder. It is a part of the bus fabric.
--- Quote End ---

Does "freely available" = cost nothing and is not time limited and works with free web edition?
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
The bridge is required when you want to connect an external (i.e. off-chip) peripheral
--- Quote End ---

In this case is the DRAM controller not an on chip peripheral? My system is as follows:

I have an external AVR micro which I want to connect to the DRAM. I also have an external video decoder chip which I want to connect to DRAM. I use the SOPC DRAM controller and link it to an Avalon master that I created. The master has external address,data and control lines. I now want to use some FPGA logic to connect decoder and micro to this Avalon master. Is this where the bridge comes in? I looked at the bridge component but did not see any option to add non avalon lines?
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
Does "freely available" = cost nothing and is not time limited and works with free web edition?
--- Quote End ---

Yes. Please understand Tri-state bridge is not an IP core. It is an essential part of Avalon fabric.
Altera_Forum
Honored Contributor
17 years ago
--- Quote Start ---
In this case is the DRAM controller not an on chip peripheral? My system is as follows:

I have an external AVR micro which I want to connect to the DRAM. I also have an external video decoder chip which I want to connect to DRAM. I use the SOPC DRAM controller and link it to an Avalon master that I created. The master has external address,data and control lines. I now want to use some FPGA logic to connect decoder and micro to this Avalon master. Is this where the bridge comes in? I looked at the bridge component but did not see any option to add non avalon lines?
--- Quote End ---

So as I understand, you have "a DRAM controller in the SOPC system" and your external devices will be communicating with this *DRAM controller only* rather than the cpu, or so to say Avalon bus, itself. You don't need a Tri-state bridge in this case (as your external devices are not communicating with the Avalon bus directly).
Altera_Forum
Honored Contributor
17 years ago
Thanks for all your help :)
Altera_Forum
Honored Contributor
17 years ago
notme,

Not sure if you've already figured this out since the post is kinda old. But here's the link to an Avalon Master template. There's also a corresponding Avalon Slave template. Hope that helps.

http://www.altera.com/support/examples/nios2/exm-avalon-mm.html

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Creating an Avalon Master - Please Help

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